JP6254384B2 - Artificial soil medium - Google Patents

Description

  The present invention relates to an artificial soil medium that can be used in a plant factory or the like.

  In recent years, plant factories that grow plants such as vegetables in an environment where growth conditions are controlled are increasing. The plant factories so far have mainly focused on hydroponic cultivation of leafy vegetables such as lettuce, but recently there is a movement to try cultivation of root vegetables that are not suitable for hydroponic cultivation in plant factories. In order to cultivate root vegetables in a plant factory, it is necessary to develop artificial soil with excellent basic performance as soil. In particular, in artificial soil, ease of handling that is difficult to realize in natural soil is required, such as increasing water retention and reducing the number of watering times for plants.

  As a technique related to artificial soil that has been developed so far, there has been a soil conditioner in which a plant natural organic material such as peat moss and a mineral material such as zeolite are dispersed and mixed as a water retention agent (see Patent Document 1). ). Since the soil conditioner of patent document 1 contains mineral materials, such as a zeolite, as a water retention agent, it is supposed that the soil with poor water retention can be improved.

  Moreover, there was artificial soil in which granular concrete crushed material and granular palm chips were mixed (see Patent Document 2). The artificial soil of Patent Document 2 is said to improve the water permeability of the soil because it mixes granular concrete crushed material, and further mixes the granular palm chips.

Japanese Patent Application Laid-Open No. 11-209760 JP 2006-20590 A

  In developing an artificial soil culture medium, a function capable of maintaining water retention and air permeability appropriately while achieving plant growth ability equivalent to natural soil is required. In particular, achieving high water retention while maintaining air permeability is important for reducing the number of watering times for plants and realizing an optimal cultivation schedule according to the type of plant. The air permeability and water retention of the artificial soil medium are deeply related to the gaps formed between the artificial soil particles. By maintaining these gaps in an optimal state, high water retention is achieved while maintaining the air permeability. Can do. In addition, artificial soil particles can be configured to retain water in the artificial soil particles, so by adjusting the water retention capacity of the artificial soil particles, added value with higher water retention not found in natural soil High artificial soil medium can be realized.

  In Patent Document 1, zeolite is dispersed and mixed as a water retention agent. However, since zeolite is likely to become lumps, appropriate air permeability cannot always be maintained. Further, if compaction or the like occurs during operations such as watering, there is a risk that the air permeability and water retention capacity of the artificial soil will be reduced.

  In Patent Document 2, air permeability and water retention are ensured by mixing crushed granular concrete and granular palm chips. However, since water retention depends on the moisture absorption and release characteristics of the granular palm chips, The soil as a whole can maintain only a certain amount of water retention, and it is difficult to achieve high water retention.

  The present invention has been made in view of the above problems, and its purpose is to provide a high water retention capacity while maintaining air permeability in an artificial soil medium containing a plurality of types of artificial soil particles. An object of the present invention is to provide an artificial soil medium capable of continuously supplying water to a plant over a long period of time.

The characteristic configuration of the artificial soil culture medium according to the present invention for solving the above problems is as follows.
An artificial soil medium containing first artificial soil particles and second artificial soil particles having different moisture absorption and release characteristics and sizes,
The first artificial soil particles have higher moisture absorption / release characteristics than the second artificial soil particles and are configured to have a larger size.

  According to the artificial soil culture medium of this configuration, since the above-described configuration is provided, the moisture release characteristics of various artificial soil particles are superimposed, and the moisture release characteristics of the respective artificial soil particles are complemented with each other. Release characteristics are obtained. Moreover, since the artificial soil culture medium of this structure is densely filled with the second artificial soil particles in the space formed between the first artificial soil particles, water can be efficiently retained in the artificial soil culture medium. As a result, compared to an artificial soil medium composed of a single artificial soil particle, water can be continuously supplied to the plant to be cultivated over a long period of time, and the frequency of watering can be reduced.

In the artificial soil medium according to the present invention,
It is preferable that the first artificial soil particles are configured as a fiber mass formed by collecting fibers, and the second artificial soil particles are configured as a porous body formed by collecting fillers.

  According to the artificial soil medium of this configuration, since the first artificial soil particles are configured as a fiber mass formed by collecting fibers, the first artificial soil particles have high moisture absorption and release characteristics, and the second artificial soil particles collect fillers. Since it is configured as a porous body, it has moderate moisture absorption / release characteristics. The artificial soil culture medium of this structure can hold | maintain water effectively to each artificial soil particle, and it becomes possible to supply a water | moisture content continuously over a long term to the plant of cultivation object. As a result, the frequency of watering can be reduced.

In the artificial soil medium according to the present invention,
It is preferable that the ratio between the particle diameter of the first artificial soil particles and the particle diameter of the second artificial soil particles is 2: 1 to 32: 1.

  According to the artificial soil culture medium of this configuration, since the above configuration is provided, the second artificial soil particles are more densely packed in the space formed between the first artificial soil particles while ensuring sufficient air permeability of the artificial soil culture medium. Can be filled. As a result, high water retention can be achieved while ensuring sufficient air permeability of the artificial soil culture medium.

In the artificial soil medium according to the present invention,
The mixing ratio of the first artificial soil particles and the second artificial soil particles is preferably 70:30 to 30:70.

  According to the artificial soil particle of this configuration, since it has the above configuration, the moisture absorption / release characteristics of various artificial soil particles are effectively superimposed, and the moisture absorption / release characteristics of each artificial soil particle are effectively complemented. In addition, a broader moisture release characteristic is obtained. As a result, it becomes possible to supply moisture continuously to the plant to be cultivated over a long period of time, and the frequency of watering can be greatly reduced.

In the artificial soil medium according to the present invention,
It is preferable that ion exchange capacity is imparted to at least one of the first artificial soil particles and the second artificial soil particles.

  According to the artificial soil culture medium of this structure, since the ion exchange capacity is imparted to at least one of the artificial soil particles, it exhibits excellent fertilizer retention and appropriately supplies nutrients to the plant to be cultivated can do.

FIG. 1 is an explanatory view conceptually showing an artificial soil medium containing two types of artificial soil particles. FIG. 2 is a conceptual diagram of artificial soil particles constituting the artificial soil culture medium.

  Hereinafter, the embodiment regarding the artificial soil culture medium which concerns on this invention is described based on FIG.1 and FIG.2. However, the present invention is not intended to be limited to the configurations described in the embodiments and drawings described below.

<Artificial soil medium>
FIG. 1 is an explanatory diagram conceptually showing an artificial soil culture medium 100 including two types of artificial soil particles 50a and 50b according to an embodiment of the present invention. In FIG. 1, the structure of the artificial soil particle 50b is shown in a simplified manner. FIG. 2 is a conceptual diagram of the artificial soil particles 50 a and 50 b that constitute the artificial soil culture medium 100. The artificial soil particle 50 includes a first artificial soil particle 50a that aggregates the fibers 1 into a fiber lump and a second artificial soil particle 50b that aggregates the fillers 2 into a porous body. The artificial soil medium 100 is composed of two types of artificial soil particles 50a and 50b having different moisture release characteristics. Here, “moisture absorption characteristics” and “moisture release characteristics” are represented by physical quantities and times related to moisture such as moisture absorption, moisture absorption timing, moisture release, moisture release timing, water retention, and moisture content. In this specification, the “water absorption characteristics” and the “water release characteristics” are defined as “moisture absorption characteristics”. Since the first artificial soil particles 50a are fiber aggregates, they have high moisture absorption / release characteristics. The first artificial soil particles 50a quickly absorb the water present in the artificial soil medium 100, and when the amount of water present in the gap 3 formed between the artificial soil particles decreases, 50a is discharged outside. On the other hand, the second artificial soil particle 50b has a gentle moisture absorption / release characteristic. Since the second artificial soil particle 50b is a porous body, the water present in the artificial soil medium 100 is gradually absorbed into the pores of the porous body, and the water present in the gap 3 formed between the artificial soil particles. When the amount decreases, the water is gradually released because the water holding ability of the pores of the porous body is strong. That is, when the artificial soil culture medium 100 has a high moisture content in the soil, the first artificial soil particles 50a that are fiber aggregates absorb water quickly, and the water retention amount of the artificial soil particles 50a increases. The second artificial soil particles 50b are gradually absorbing water. Thereby, the gas phase of the gap 3 formed between the artificial soil particles can be secured. On the other hand, when the water content of the soil is small, the first artificial soil particles 50a that are fiber aggregates quickly release water, and the amount of water held by the first artificial soil particles 50a decreases. The water held in the second artificial soil particle 50b which is the body is gradually released out of the second artificial soil particle 50b. Therefore, the artificial soil culture medium 100 of the present invention has a very broad moisture absorption / release characteristic.

  As shown in FIG. 1, the artificial soil culture medium 100 is set so that the particle size of the first artificial soil particles 50a is larger than the particle size of the second artificial soil particles 50b. Accordingly, the second artificial soil particles 50b are densely filled between the first artificial soil particles 50a. In general, natural soil has gaps between soil particles, which are related to the gas phase rate. When the size of the gap is increased, the gas phase rate is increased, but the water retention ability is decreased, and there is a tendency that the water available for the plant is reduced. On the other hand, when the size of the gap is reduced, the water retention capability is increased, but the gas phase rate is lowered and there is a possibility that the root rot of the plant occurs. On the other hand, the artificial soil culture medium 100 can hold the gas and moisture in the artificial soil particle 50 itself even if the size of the gap 3 between the artificial soil particles 50 is set to be small. The phase ratio does not decrease. Moreover, if the gap 3 formed between the artificial soil particles 50 is reduced, a certain amount of water is held in the gap 3 itself by capillary action, and the water retention capacity of the entire artificial soil medium 100 is further increased. Become.

  The ratio between the particle size of the first artificial soil particle 50a and the particle size of the second artificial soil particle 50b is preferably 2: 1 to 32: 1, more preferably 2: 1 to 7: 1. When the ratio of the particle size of the first artificial soil particle 50a and the particle size of the second artificial soil particle 50b is set so that the second artificial soil particle 50b is larger than 2: 1, between the artificial soil particles 50 The formed gap 3 becomes too large and sufficient water retention cannot be obtained, which may adversely affect the growth of cultivated plants. On the other hand, when the ratio of the particle size of the first artificial soil particle 50a and the particle size of the second artificial soil particle 50b is set so that the second artificial soil particle 50b is smaller than 32: 1, the artificial soil particle 50 However, there is a possibility that root rot of the cultivated plant may occur due to poorly filled air.

  The mixing ratio of the first artificial soil particles 50a and the second artificial soil particles 50b is preferably 70:30 to 30:70, and more preferably 70:30 to 50:50. If the mixing ratio of the first artificial soil particles 50a and the second artificial soil particles 50b is set so that the ratio of the second artificial soil particles 50b is less than 70:30, the gap 3 formed between the artificial soil particles 50 Becomes too large to obtain sufficient water retention, which may adversely affect the growth of cultivated plants. On the other hand, when the mixing ratio of the first artificial soil particles 50a and the second artificial soil particles 50b is set so that the ratio of the second artificial soil particles 50b is larger than 30:70, the artificial soil particles 50 are densely packed. After that, there is a possibility that the air permeability becomes poor and the root decay of the cultivated plant occurs.

[First artificial soil particles]
The 1st artificial soil particle 50a of Fig.2 (a) is comprised as a fiber lump. The fiber lump is a collection of a plurality of fibers 1. Gaps 6 are formed between the fibers 1 constituting the fiber mass. The fiber lump can retain moisture in the gap 6. Therefore, the state of the voids 6 in the fiber lump is related to the water retention of the fiber lump. The state of the void 6 can be adjusted by changing the amount (density) of the fibers 1 used to form the fiber mass, the type, thickness, length, etc. of the fibers 1. The size of the fiber 1 is preferably 1 to 200 μm in thickness and 0.01 to 10 mm in length.

  The particle diameter of the first artificial soil particles 50a is 2.0 to 12.0 mm, preferably 3.0 to 11.0 mm, and more preferably 4.0 to 10.0 mm. The adjustment of the particle diameter of the first artificial soil particles 50a can be performed, for example, by classification with a sieve. When the particle diameter of the first artificial soil particles 50a is less than 2.0 mm, the amount of water retained in the first artificial soil particles 50a is reduced, and the water retention of the artificial soil medium 100 may not be sufficiently increased. On the other hand, when the particle diameter of the first artificial soil particles 50a exceeds 12.0 mm, the space formed between the first artificial soil particles 50a is too finely filled with the second artificial soil particles 50b, resulting in poor air permeability. There is a fear. The particle diameter of the first artificial soil particles 50a can be measured, for example, using an optical microscope observation and an image processing method.

  It is preferable to use a hydrophilic fiber as the fiber 1 because the fiber mass is configured so that moisture can be retained therein. As the type of the fiber 1, natural fiber or synthetic fiber is appropriately selected. Preferred hydrophilic fibers include, for example, cotton, wool, rayon, and cellulose fibers as natural fibers, and synthetic fibers include, for example, vinylon, urethane, nylon, and acetate. Among these, cotton, cellulose fibers, And vinylon is more preferred. What mixed the natural fiber and the synthetic fiber may be used.

  In forming the fiber lump, it is also possible to introduce another water retention material (hereinafter referred to as a second water retention material to distinguish it from the fiber 1 as the water retention material) between the fibers 1. In this case, the fiber lump can be provided with water retention by the second water retention material in addition to the water retention by the gaps 6 between the fibers 1 originally possessed. As a method for introducing the second water retention material into the fiber mass, for example, the fiber 1 is formed by granulating the fibers 1 and the second water retention material is added during granulation. Moreover, you may coat the surface of the fiber 1 with a 2nd water retention material. The second water retaining material introduced into the fiber mass by these methods is preferably exposed in the gaps 6 between the fibers 1. In this case, the fiber lump significantly improves the water retention capacity of the gap 6.

  As the second water retaining material, a polymer water retaining material having water absorption can be used. For example, polyacrylate polymer, polysulfonate polymer, polyacrylamide polymer, polyvinyl alcohol polymer, polyalkylene oxide polymer and other synthetic polymer water retention materials, polyaspartate polymer, polyglutamate Natural polymer water-retaining materials such as polymer, polyalginate polymer, cellulose polymer and starch. These 2nd water retention materials can also be used in combination of 2 or more types. Moreover, it is also possible to use porous materials, such as diatomaceous earth, foam glass, a foam metal, activated carbon, and ceramics, as a 2nd water retention material.

  The fiber lump is formed by a known granulation method. For example, long fibers are aligned with a carding device or the like, cut to a length of about 3 to 10 mm, and the produced fibers are tumbled granulated, fluidized bed granulated, stirred granulated, compressed granulated, extruded granulated, etc. It forms by granulating by the method of. During granulation, the fiber 1 may be mixed with a binder such as a resin or glue, but the fibers 1 are entangled with each other and easily fixed, so that the fibers 1 can be agglomerated even when no binder is used. Can be processed.

  In granulating the fiber mass, it is also possible to use short fibers or fiber powder as the fibers 1. In this case, the resin emulsion is added in small amounts as a binder and granulated while stirring the short fibers and fiber powder with a stirring and mixing granulator. Thereby, the short fiber and fiber powder which form a fiber lump are fixed in part, and the strong base 10 can be formed.

  As the binder, either an organic binder or an inorganic binder can be used. Organic binders include, for example, synthetic resin binders such as polyolefin binders, polyvinyl alcohol binders, polyurethane binders, polyvinyl acetate binders, polysaccharides such as starch, carrageenan, xanthan gum, gellan gum, alginic acid, and animal properties such as glue. Examples include natural product-based binders such as proteins. Examples of the inorganic binder include silicate binders such as water glass, phosphate binders such as aluminum phosphate, borate binders such as aluminum borate, and hydraulic binders such as cement. An organic binder and an inorganic binder can be used in combination of two or more.

  A coating layer may be formed on the outer surface of the fiber lump. By providing the coating layer, rapid drying of the fiber mass can be prevented, and moisture absorption / release characteristics can be controlled. The coating layer is a film having ultrafine pores through which water molecules can pass. Or it can also be set as the permeable membrane which water | moisture content permeates from one side and can move to the other side. A coating layer is formed in the outer surface part of a fiber lump by the following methods, for example. First, the granulated fiber lump is transferred to a container, and water about half the volume (occupied volume) of the fiber lump is added to immerse the water in the gap 6 of the fiber lump. Next, a resin emulsion of 1/20 to 1/2 of the volume of the fiber lump is added to the fiber lump soaked with water. Additives such as pigments, fragrances, bactericides, antibacterial agents, deodorants, and insecticides may be mixed in the resin emulsion. Next, the resin emulsion is impregnated from the outer surface of the fiber lump while rolling so that the resin emulsion uniformly adheres to the outer surface of the fiber lump. At this time, since the water has soaked into the center of the fiber lump, the resin emulsion remains near the outer surface of the fiber lump. Thereafter, the fiber lump to which the resin emulsion is adhered is dried in an oven, the resin is then melted, and the resin is fused to the fibers 1 near the outer surface of the fiber lump to form a resin film as a coating layer. Thereby, the 1st artificial soil particle 50a which coat | covered the outer surface part of the fiber lump with the coating layer is completed. In the coating layer, when the resin melts, the solvent contained in the resin emulsion is evaporated, and a porous structure is formed. The obtained first artificial soil particles 50a are dried and classified as necessary to adjust the particle size. The coating layer is formed so as to have a thickness that penetrates slightly from the outer surface of the fiber lump so as to reinforce the entangled portions of the fibers 1 constituting the fiber lump (where the fibers 1 are in contact with each other). Also good. Thereby, the intensity | strength and durability of the 1st artificial soil particle 50a can be improved. The film thickness of a coating layer is set to 1-200 micrometers, Preferably it is set to 10-100 micrometers, More preferably, it is set to 20-60 micrometers.

  The material of the coating layer is preferably insoluble in water and hardly oxidized, and examples thereof include a resin material. Examples of such a resin material include polyolefin resins such as polyethylene and polypropylene, vinyl chloride resins such as polyvinyl chloride and polyvinylidene chloride, polyester resins such as polyethylene terephthalate, and styrene resins such as polystyrene. Of these, polyethylene is preferred. In place of the resin material, a synthetic polymer gelling agent such as polyethylene glycol or a natural gelling agent such as sodium alginate can be used.

  An ion exchange ability can also be imparted to the fiber mass and the coating layer. By providing ion exchange capacity to at least one of the fiber lump and the coating layer, the first artificial soil particles 50a can carry the fertilizer component necessary for plant growth, so that the plant is equivalent to natural soil. It becomes possible to realize artificial soil having a growing ability.

[Second artificial soil particle]
The 2nd artificial soil particle 50b of FIG.2 (b) consists of a porous body. The porous body is a granular material in which a plurality of fillers 2 are aggregated. It is not essential that the plurality of fillers 2 are in contact with each other. If a relative positional relationship within a certain range is maintained in one particle via a binder or the like, the plurality of fillers 2 are aggregated. It can be considered that it has become granular.

  The particle diameter of the second artificial soil particles 50b is 0.1 to 2.0 mm, preferably 0.25 to 2.0 mm. Adjustment of the particle size of the second artificial soil particles 50b can be performed, for example, by classification with a sieve. When the particle size of the second artificial soil particles 50b is less than 0.1 mm, the gap 3 between the second artificial soil particles 50b is reduced and the drainage performance is reduced, so that the plant to be cultivated hardly absorbs oxygen from the roots. There is a risk of becoming. On the other hand, if the particle diameter of the second artificial soil particles 50b exceeds 2.0 mm, the gap 3 between the second artificial soil particles 50b may be large and sufficient water retention may not be obtained. The particle diameter of the second artificial soil particles 50b can be measured using, for example, optical microscope observation and an image processing method.

  The filler 2 constituting the porous body of the second artificial soil particle 50b has a large number of pores 4 from the surface to the inside. The pore 4 includes various forms. For example, when the filler 2 is the zeolite shown in FIG. 1, voids present in the crystal structure of the zeolite are the pores 4. In addition, when the filler 2 is hydrotalcite or bentonite (not shown), the layers existing in the layer structure of the hydrotalcite or bentonite are the pores 4. That is, in the present invention, “pores” mean voids, interlayers, spaces, etc. existing in the structure of the filler 2, and these are not limited to “pore-like” forms.

  The size of the pores 4 of the filler 2 is on the order of sub-nm to sub-μm. When the filler 2 is the zeolite shown in FIG. 2B, the size (diameter) of the voids existing in the crystal structure of the zeolite is about 0.3 to 1.3 nm. When the filler 2 is hydrotalcite, the size (distance) between layers existing in the layer structure of the hydrotalcite is about 0.3 to 3.0 nm. In addition, an organic porous material can also be used as the filler 2, and the pore diameter in that case is about 0.1 to 0.8 μm. The size of the pores 4 of the filler 2 is optimal using a gas adsorption method, a mercury intrusion method, a small-angle X-ray scattering method, an image processing method, or a combination of these methods depending on the state of the measurement object. Measured by the method.

  Between the plurality of fillers 2, communication holes 5 of sub μm order to sub mm order capable of holding moisture are formed. The pores 4 are dispersedly arranged around the communication hole 5. Since moisture is mainly retained in the communication hole 5, the second artificial soil particle 50b can be provided with a certain water retention. The size of the communication hole 5 (the average value of the distance between the fillers 2) can vary depending on the type, composition, and granulation conditions of the filler 2 and the binder, but is on the order of sub μm to sub mm. When the filler 2 is the zeolite shown in FIG. 2B, the size of the communication hole 5 is 0.1 to 20 μm. The size of the communication hole 5 is measured by an optimum method using a gas adsorption method, a mercury intrusion method, a small-angle X-ray scattering method, an image processing method, or a combination of these methods according to the state of the measurement object. can do.

  As the filler 2, it is preferable to use a material in which the pores 4 are provided with ion exchange capacity so that the second artificial soil particles 50b have sufficient fertilizer. In this case, as the material imparted with ion exchange ability, a material imparted with cation exchange ability, a material imparted with anion exchange ability, or a mixture of both can be used. In addition, a porous material having no ion exchange ability (for example, a polymer foam, a glass foam, etc.) is prepared separately, and a material in which the ion exchange ability is imparted to the pores 4 of the porous material is prepared. It is also possible to use the filler 2 by introducing it by press-fitting or impregnation. Examples of the material imparted with the cation exchange ability include cation exchange minerals, humus, and cation exchange resins. Examples of the material imparted with the anion exchange ability include anion exchange minerals and anion exchange resins.

  Examples of cation exchange minerals include smectite minerals such as montmorillonite, bentonite, beidellite, hectorite, saponite, and stevensite, mica minerals, vermiculite, and zeolite. Examples of the cation exchange resin include a weak acid cation exchange resin and a strong acid cation exchange resin. Of these, zeolite or bentonite is preferable. The cation exchange mineral and the cation exchange resin can be used in combination of two or more. The cation exchange capacity of the cation exchange mineral and the cation exchange resin is set to 10 to 700 meq / 100 g, preferably 20 to 700 meq / 100 g, and more preferably 30 to 700 meq / 100 g. When the cation exchange capacity is less than 10 meq / 100 g, the nutrients cannot be taken in sufficiently, and the taken-up nutrients may be lost early due to irrigation or the like. On the other hand, even if the fertilizer is excessively increased so that the cation exchange capacity exceeds 700 meq / 100 g, the effect is not greatly improved and it is not economical.

  Anion-exchange minerals include, for example, natural layered double hydroxides that have double hydroxides as the main skeleton such as hydrotalcite, manaceite, pyroaulite, sjoglenite, patina, synthetic hydrotalcite and hydrotalcite-like Materials, clay minerals such as allophane, imogolite, kaolin and the like. Examples of the anion exchange resin include weakly basic anion exchange resins and strong basic anion exchange resins. Of these, hydrotalcite is preferred. An anion exchange mineral and an anion exchange resin can be used in combination of two or more. The anion exchange capacity of the anion exchange mineral and the anion exchange resin is set to 5 to 500 meq / 100 g, preferably 20 to 500 meq / 100 g, and more preferably 30 to 500 meq / 100 g. When the anion exchange capacity is less than 5 meq / 100 g, the nutrients cannot be taken in sufficiently, and the taken-up nutrients may be lost early due to irrigation or the like. On the other hand, even if the fertilizer is excessively increased so that the anion exchange capacity exceeds 500 meq / 100 g, the effect is not greatly improved and it is not economical.

  When the filler 2 is an inorganic natural mineral such as zeolite or hydrotalcite, the gelling of the polymer gelling agent is performed in order to collect a plurality of fillers 2 to form a granular material (second artificial soil particle 50b). Reaction is preferably used. Examples of the gelation reaction of the polymer gelling agent include a gelation reaction between an alginate and a polyvalent metal ion, a gelation reaction of carboxymethylcellulose (CMC), and a gel formed by a double helical structure reaction of a polysaccharide such as carrageenan. Reaction. Among these, the gelation reaction between an alginate and a polyvalent metal ion will be described. Sodium alginate, which is one of alginates, is a neutral salt in which the carboxyl group of alginic acid is bonded to Na ions. Alginic acid is not required in water, but sodium alginate is water soluble. When an aqueous sodium alginate solution is added to an aqueous solution of polyvalent metal ions (for example, Ca ions), ionic crosslinking occurs between the molecules of sodium alginate and gelation occurs. In the case of this embodiment, the gelation reaction can be performed by the following steps. First, an alginate aqueous solution is prepared by dissolving alginate in water, filler 2 is added to the alginate aqueous solution, and this is sufficiently stirred to form a mixed solution in which filler 2 is dispersed in the alginate aqueous solution. . Next, the mixed solution is dropped into the polyvalent metal ion aqueous solution, and the alginate contained in the mixed solution is gelled in a granular form. Thereafter, the gelled particles are collected, washed with water, and sufficiently dried. Thereby, the artificial soil particle 50b as a granular material which the filler 2 disperse | distributed in the alginic acid gel formed from an alginate and a polyvalent metal ion is obtained.

  Examples of alginates that can be used in the gelation reaction include sodium alginate, potassium alginate, and ammonium alginate. These alginate can be used in combination of two or more. The concentration of the alginate aqueous solution is 0.1 to 5% by weight, preferably 0.2 to 5% by weight, and more preferably 0.2 to 3% by weight. When the concentration of the alginate aqueous solution is less than 0.1% by weight, the gelation reaction hardly occurs. When the concentration exceeds 5% by weight, the viscosity of the alginate aqueous solution becomes too large. In addition, it is difficult to drop the mixed solution into the aqueous solution of the polyvalent metal ion.

  The polyvalent metal ion aqueous solution to which the alginate aqueous solution is dropped may be a divalent or higher metal ion aqueous solution that reacts with the alginate and causes gelation. Examples of such polyvalent metal ion aqueous solutions include aqueous chloride solutions of polyvalent metals such as calcium chloride, barium chloride, strontium chloride, nickel chloride, aluminum chloride, iron chloride, cobalt chloride, calcium nitrate, barium nitrate, aluminum nitrate. Nitrate aqueous solutions of polyvalent metals such as iron nitrate, copper nitrate and cobalt nitrate, lactate aqueous solutions of polyvalent metals such as calcium lactate, barium lactate, aluminum lactate and zinc lactate, aluminum sulfate, zinc sulfate, cobalt sulfate etc. An aqueous solution of a valent metal sulfate is mentioned. These polyvalent metal ion aqueous solutions can be used in combination of two or more. The concentration of the polyvalent metal ion aqueous solution is 1 to 20% by weight, preferably 2 to 15% by weight, and more preferably 3 to 10% by weight. When the concentration of the polyvalent metal ion aqueous solution is less than 1% by weight, the gelation reaction hardly occurs. When the concentration exceeds 20% by weight, it takes time to dissolve the metal salt and excessive materials are used. Not economical.

  The granulation of the filler 2 for forming the second artificial soil particles 50b can be performed by a granulation method using a binder in addition to the gelation reaction described above. This includes, for example, adding a binder or a solvent to the filler 2 and mixing, introducing the mixture into a granulator, rolling granulation, fluidized bed granulation, stirring granulation, compression granulation, extrusion granulation, crushing It can carry out by well-known granulation methods, such as granulation, melt granulation, and spray granulation. The obtained granulated body is dried and classified as necessary, and the second artificial soil particle 50b is completed. In addition, a binder is added to the filler 2 and, if necessary, a solvent or the like is added and kneaded. The resulting dried block is pulverized as appropriate with a mortar, pestle, hammer mill, roll crusher or the like. It is also possible to obtain a granular material. The granular material can be used as the second artificial soil particle 50b as it is, but it is preferable to adjust to a desired particle size by sieving.

  As the binder, either an organic binder or an inorganic binder can be used. Organic binders include, for example, synthetic resin binders such as polyolefin binders, polyvinyl alcohol binders, polyurethane binders, polyvinyl acetate binders, polysaccharides such as starch, carrageenan, xanthan gum, gellan gum, alginic acid, and animal properties such as glue. Examples include natural product-based binders such as proteins. Examples of the inorganic binder include silicate binders such as water glass, phosphate binders such as aluminum phosphate, borate binders such as aluminum borate, and hydraulic binders such as cement. An organic binder and an inorganic binder can be used in combination of two or more.

  When the filler 2 is an organic porous material, the formation of the second artificial soil particles 50b may be performed by the same method as the granulation method of the filler 2 described above using a binder. The second artificial soil particle 50b is formed by heating to a temperature equal to or higher than the melting point of the organic porous material (polymer material, etc.) constituting the material 2 and thermally fusing the surfaces of the plurality of fillers 2 together. It is also possible to do. In this case, a granular material in which a plurality of fillers 2 are gathered can be obtained without using a binder. As such an organic porous material, for example, an organic polymer foam obtained by foaming an organic polymer material such as polyethylene, polypropylene, polyurethane, polyvinyl alcohol, and cellulose, and the powder of the organic polymer material is heated and melted. An organic polymer porous body having an open cell structure is exemplified.

  In addition, although not shown in figure, it is also possible to provide the coating layer similar to the 1st artificial soil particle 50a in the outer surface part of the porous body of the 2nd artificial soil particle 50b. By providing the covering layer, it is possible to more precisely control the moisture absorption / release characteristics of the second artificial soil particles 50b.

  Next, the Example using the artificial soil culture medium of this invention is described. In the examples, changes in water retention and air permeability characteristics due to differences in the artificial soil medium were measured and evaluated. The 1st artificial soil particle and the 2nd artificial soil particle were produced with the following method. Furthermore, the artificial soil culture medium used for an Example and a comparative example was prepared using the 1st artificial soil particle and / or the 2nd artificial soil particle.

[Production of first artificial soil particles]
As the first artificial soil particles used in the examples, three different types of first artificial soil particles were prepared using two types of fibers, and used for an artificial soil medium. Three types of first artificial soil particles were produced by the following method.

(Vinylon fiber ball)
A polyethylene emulsion (Separjon (registered trademark) G315) with an apparent volume of 1000 cc vinylon short fibers (length: 0.5 mm, manufactured by Kuraray Co., Ltd.) stirred and rolled with a stirring and mixing granulator (manufactured by G-Labo Co., Ltd.) , Manufactured by Sumitomo Seika Co., Ltd., concentration of about 40% by weight) was added and granulated to form a granular fiber mass impregnated with polyethylene emulsion inside. Next, the same polyethylene emulsion was added so as to be ½ of the volume, and impregnated while rolling so that the emulsion adhered uniformly to the outer surface. After the fiber lump impregnated with the emulsion was dried in an oven at 60 ° C., the short fibers were fixed by melting the polyethylene in the emulsion at 100 ° C. and fusing the fibers to obtain first artificial soil particles. . The particle diameter of the first artificial soil particles was in the range of 0.5 to 11.2 mm.

(Cellulose fiber sphere)
Cellulose fibers (Avocel B800, manufactured by Showa Chemical Industry Co., Ltd.) are aligned with a carding device, cut to a length of about 3 to 10 mm, put between two rotating plates, rolled into a polyethylene emulsion ( Sepouljon (registered trademark) G315, manufactured by Sumitomo Seika Co., Ltd., concentration 40% by weight) is added and granulated to form a granular fiber mass impregnated with polyethylene emulsion inside did. Next, the same polyethylene emulsion was added so as to be ½ of the volume, and impregnated while rolling so that the emulsion adhered uniformly to the outer surface. After the fiber mass impregnated with the emulsion is dried in an oven at 60 ° C., the polyethylene in the emulsion is melted and fused to the fibers at 100 ° C., thereby fixing the cellulose fibers to obtain first artificial soil particles. It was. The size of the first artificial soil particles was prepared to be in the range of ˜8 mm.

(Cellulose and vinylon blended spheres)
Cellulose fibers (Avocel B800, manufactured by Showa Chemical Industry Co., Ltd.) were aligned with a carding device and cut to a length of about 3 to 10 mm. Next, while adding the same amount of cellulose fiber and short vinylon fiber (length: 0.5 mm, manufactured by Kuraray Co., Ltd.) between the two rotating plates, a polyethylene emulsion (Separjon (registered trademark) G315, Sumitomo Seiki) was added. The product was granulated by adding about 10 times the concentration (made by Kasei Co., Ltd., concentration: 40% by weight) to form a granular fiber mass impregnated with a polyethylene emulsion. Next, the same polyethylene emulsion was added so as to be ½ of the volume, and impregnated while rolling so that the emulsion adhered uniformly to the outer surface. After drying the fiber lump impregnated with the emulsion at 60 ° C. in an oven, the fibers in the emulsion were melted and fused to the fibers at 100 ° C., thereby fixing the fibers to obtain first artificial soil particles. . The size of the first artificial soil particles was prepared to be in the range of 0.5 to 1 mm.

[Production of second artificial soil particles]
Zeolite and hydrotalcite were used as fillers, sodium alginate was used as the alginate, and 5% calcium chloride aqueous solution was used as the polyvalent metal ion aqueous solution. A reagent sodium alginate manufactured by Wako Pure Chemical Industries, Ltd. is dissolved in water to prepare an aqueous solution having a concentration of 0.5%, and an artificial zeolite “Ryukyu Light 600 made by Ecowell Co., Ltd. 10 parts by weight and 10 parts by weight of a reagent hydrotalcite manufactured by Wako Pure Chemical Industries, Ltd. were added and mixed. The mixed solution was dropped into a 5% calcium chloride aqueous solution at a rate of 1 drop / second. After the dropped droplets were gelled, the particulate gel was recovered, washed with water, and dried for 24 hours with a dryer set at 55 ° C. Moreover, when producing the artificial soil particle | grains of a particle size smaller than 0.1 mm, the dried granular material was grind | pulverized with the mortar etc. and produced. The particle size of the artificial soil particles was 11.2 mm or less.

[Evaluation of water retention and air permeability of artificial soil medium by combination of different artificial soil particles]
The artificial soil culture media of Examples 1 to 10 were prepared so that the particle size of the first artificial soil particles was larger than the particle size of the second artificial soil particles. The artificial soil culture media of Comparative Examples 1 to 9 were prepared using either the first artificial soil particle or the second artificial soil particle alone, or the particle diameter of the second artificial soil particle is the particle size of the first artificial soil particle. What was prepared so that it might become larger than was used. Details of each example and comparative example are shown below.
(1) Example 1: First artificial soil particles (vinylon fiber spheres) having a particle size of 8 to 11.2 mm and second artificial soil particles having a particle size of 1 to 2 mm were prepared. The blending ratio with soil particles was adjusted to 50:50.
(2) Example 2: First artificial soil particles (vinylon fiber spheres) having a particle size of 8 to 11.2 mm and second artificial soil particles having a particle size of 0.1 to 0.5 mm were prepared. The mixing ratio of the second artificial soil particles was adjusted to 50:50.
(3) Example 3: First artificial soil particles (vinylon fiber spheres) having a particle size of 2 to 4 mm and second artificial soil particles having a particle size of 0.5 to 2 mm were prepared. The blending ratio with soil particles was adjusted to 50:50.
(4) Example 4: First artificial soil particles (vinylon fiber spheres) having a particle size of 2 to 11.2 mm and second artificial soil particles having a particle size of 0.5 to 2 mm were prepared. The blending ratio with the two artificial soil particles was adjusted to 50:50.
(5) Example 5: First artificial soil particles (vinylon fiber spheres) having a particle size of 2 to 11.2 mm and second artificial soil particles having a particle size of 0.5 to 1 mm were prepared. The blending ratio with the two artificial soil particles was adjusted to 50:50.
(6) Example 6: First artificial soil particles (vinylon fiber spheres) having a particle size of 4 to 6 mm and second artificial soil particles having a particle size of 0.5 to 1 mm are prepared. The blending ratio with soil particles was adjusted to 30:70.
(7) Example 7: First artificial soil particles (vinylon fiber spheres) having a particle size of 2 to 4 mm and second artificial soil particles having a particle size of 0.1 to 0.5 mm were prepared. The blending ratio with the two artificial soil particles was adjusted to 70:30.
(8) Example 8: First artificial soil particles (cellulose fiber spheres) having a particle size of 4 to 6 mm and second artificial soil particles having a particle size of 0.5 to 1 mm were prepared. The blending ratio with soil particles was adjusted to 50:50.
(9) Example 9: First artificial soil particles (cellulose fiber spheres) having a particle size of 2 to 4 mm and second artificial soil particles having a particle size of 0.1 to 0.5 mm were prepared. The blending ratio with the two artificial soil particles was adjusted to 30:70.
(10) Example 10: First artificial soil particles (cellulose-vinylon blended spheres) having a particle size of 4 to 6 mm and second artificial soil particles having a particle size of 0.5 to 1 mm are prepared. The blending ratio with the second artificial soil particles was adjusted to 70:30.
(11) Comparative Example 1: First artificial soil particles (vinylon fiber spheres) were prepared with a particle size of 8 to 11.2 mm, and an artificial soil medium was prepared with 100% of the first artificial soil particles.
(12) Comparative Example 2: First artificial soil particles (vinylon fiber spheres) were prepared to have a particle diameter of 2 to 4 mm, and an artificial soil medium was prepared with 100% of the first artificial soil particles.
(13) Comparative Example 3: First artificial soil particles (vinylon fiber spheres) were prepared to have a particle size of 0.5 to 1 mm, and an artificial soil medium was prepared with 100% of the first artificial soil particles.
(14) Comparative Example 4: First artificial soil particles (cellulose fiber spheres) were prepared to have a particle size of 5.6 to 8 mm, and an artificial soil medium was prepared with 100% of the first artificial soil particles.
(15) Comparative Example 5: Second artificial soil particles were prepared with a particle size of 1 to 2 mm, and an artificial soil medium was prepared with 100% of the second artificial soil particles.
(16) Comparative Example 6: Second artificial soil particles were prepared with a particle size of 0.1 mm or less, and an artificial soil medium was prepared with 100% of the second artificial soil particles.
(17) Comparative Example 7: First artificial soil particles (vinylon fiber spheres) having a particle size of 2 to 4 mm and second artificial soil particles having a particle size of 3.35 to 5.6 mm were prepared. The blending ratio with the two artificial soil particles was adjusted to 50:50.
(18) Comparative Example 8: First artificial soil particles (vinylon fiber spheres) having a particle size of 0.5 to 2 mm and second artificial soil particles having a particle size of 1 to 2 mm are prepared. The blending ratio with soil particles was adjusted to 50:50.
(19) Comparative Example 9: Commercially available peat moss soil (manufactured by Greenmer) was used.

<Test content>
(1) Water retention: Chromatographic tube (diameter: 30 mm, length: 300 mm) is filled with 150 cc of the soil to be tested, 100 ml of water is dropped from the upper part of the chromatographic tube, water is drained from the lower part of the chromatographic tube, and 3 minutes The weight when water did not fall from the chromatography tube was measured, and the weight of the soil to be tested, which had been measured in advance, was subtracted. This was converted into a water retention amount for 100 cc of the soil to be tested.
(2) Breathability: As the soil used for breathability, the soil of the test object whose water retention was measured was left to stand for 24 hours while being packed in a column, and was naturally dried. As a test method, 100 ml of water was dropped from the upper part of the chromatographic tube, and the time until 50 g of water was discharged from the lower part of the chromatographic tube was measured.
According to the above method, each artificial soil medium was evaluated for water retention and air permeability. The results are shown in the table below.

<Test results>
As shown in the table, the artificial soil culture medium of Examples 1 to 10 has high water retention (artificial soil) while maintaining a constant air permeability (less than 1000 seconds) as compared with the soil culture medium of Comparative Examples 1 to 9. It was shown that a water content of 45 cc or more per 100 cc of the medium was ensured, and the air permeability and water retention were balanced at a high level. On the other hand, the artificial soil culture media of Comparative Examples 1 to 6 using the first artificial soil particles or the second artificial soil particles alone have poor results in either air permeability or water retention, and air permeability and water retention. Could not be balanced. Moreover, although the high air permeability was securable about the artificial soil culture medium of the comparative examples 7 and 8 which produced the 2nd artificial soil particle larger than the 1st artificial soil particle, the improvement of water retention was not recognized.

  The artificial soil particles and artificial soil of the present invention can be used for plant cultivation performed in a plant factory or the like, but as other uses, a soil culture medium for horticulture, a soil culture medium for greening, a molded soil medium, a soil improver Etc. can also be used.

DESCRIPTION OF SYMBOLS 1 Fiber 2 Filler 50a 1st artificial soil particle 50b 2nd artificial soil particle 100 Artificial soil culture medium

Claims (4)

An artificial soil medium containing first artificial soil particles and second artificial soil particles having different moisture absorption and release characteristics and sizes,
The first artificial soil particles include a fiber mass formed by collecting fibers, and a coating layer through which water molecules provided on the outer surface of the fiber mass can pass.
The second artificial soil particles are formed by aggregating a plurality of fillers having pores, communication holes are formed between the plurality of fillers, and the pores are dispersed around the communication holes. With a porous body,
The first artificial soil particles, said second artificial soil particles by Redirecting a artificial soil media are configured to listen size. The artificial soil culture medium according to claim 1, wherein the ratio of the particle diameter of the first artificial soil particles to the particle diameter of the second artificial soil particles is 2: 1 to 32: 1. The artificial soil medium according to claim 1 or 2 , wherein a mixing ratio of the first artificial soil particles and the second artificial soil particles is 70:30 to 30:70. The artificial soil medium according to any one of claims 1 to 3 , wherein ion exchange capacity is imparted to at least one of the first artificial soil particles and the second artificial soil particles.

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